Such front derailleur devices are known from the prior art. For example, documents DE 10 2014 010 367 A1 and DE 10 2014 007 566 A1 describe front derailleur devices of this type. These are configured such that the derailleur device is pretensioned via a spring mechanism in a particular operating position, for example in the operating position of the bicycle chain in which the chain lies on the smallest chain wheel. The chain cage is in a position in which it holds the bicycle chain on the smallest chain wheel. In order to actuate the derailleur device so that the chain cage is pivoted via the hinge arrangement such that the bicycle chain is moved to the next larger chain wheel and as far as the largest chain wheel (insofar as the bicycle chain shift has more than two chain wheels), in such conventional front derailleur devices an actuating force is exerted on the derailleur device via a Bowden cable. This actuating force is sufficiently large to overcome the pretension force and thus causes a displacement of the chain cage into the desired operating position.
One essential aspect of such front derailleur devices lies in the geometric arrangement of the hinge arrangement which is pivotable relative to the frame fixing part. Normally, hinge arrangements are used with two parallel pivotable lever arms, wherein each lever arm is mounted with one end pivotably on the frame fixing part and with its other end pivotably on the chain cage. Overall, this gives a type of parallelogram mechanism so that the chain cage can be moved on an orbit in a predefined alignment. The two documents mentioned above show arrangements in which the chain cage is pivoted sideways in the manner described above in a substantially horizontal plane or in a plane tilted slightly to the horizontal. In this context, we also speak of “side swing” derailleurs.
Such “side swing” derailleur devices have been known for a long time in the prior art, for example from documents EP 0 042 274 A2 or EP 0 104 110 B1.
An essential advantage of such “side swing” derailleur devices is that they can be arranged with their mechanical components substantially to the side of the frame tube. In modern bicycles with frame geometries with short chain struts and large running wheel diameters, relatively little space is available behind the seat tube of the frame. This applies both to the mechanical components of the derailleur device itself and to components for guiding the control cable with which the derailleur device is actuated.
As an alternative to “side swing” derailleur devices, derailleurs are known in which the chain cage pivots in the vertical direction, so-called “top swing” arrangements. Such a front derailleur device is shown and described for example in document U.S. Pat. No. 4,613,319. In this arrangement, the chain cage is pivoted from a bottom position above the smallest chain wheel upward to the largest chain wheel. A similar arrangement is shown and described in document U.S. Pat. No. 4,030,374. This arrangement is also configured as a “top swing” arrangement. This document has the feature that a leaf spring is screwed to one of the hinged struts of the hinge arrangement, protrudes over the hinged strut and rests in a sprung manner on an arm. This solution is also space-consuming and has not therefore proved successful in practice.
An important aspect of modern derailleur devices lies in the inward and outward routing of the control cable. Because of the ever more complex frame geometries, conventional guide routes of the control cable, for example along the seat tube, are often no longer advantageous. It is an object of the present invention to propose a front derailleur device of the type described initially which, with simple and economic construction and reliable function, takes up little construction space and allows an advantageous guidance of the control cable.